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Catalytic Enantioselective Synthesis of 1,4-(Hetero) Dicarbonyl Compounds through α-Carbonyl Umpolung.
J Am Chem Soc
January 2025
Institute of Organic Chemistry, University of Leipzig, 04103 Leipzig, Germany.
The enantioselective synthesis of 1,4-dicarbonyl compounds continues to pose a significant challenge in organic synthesis, and a catalytic process which generates two adjacent stereogenic centers with full stereochemical control is lacking until now. The 1,4-relationship of the functional groups requires an Umpolung strategy as one of the α-carbonyl positions has to be inverted into an electrophilic center to react with a normal enolate. We report herein the highly enantio- and diastereoselective addition of silyl ketene acetals toward electrophilic 1-azaallyl cations to furnish chiral 4-hydrazonoesters, which are masked 1,4-dicarbonyl compounds.
View Article and Find Full Text PDFSimultaneous Profiling of Multiple Phosphorylated Metabolites in Typical Biological Matrices via Ion-Pair Reversed-Phase Ultrahigh-Performance Liquid Chromatography and Mass Spectrometry.
Anal Chem
January 2025
State Key Laboratory of Genetic Engineering, School of Life Sciences, Human Phenome Institute, Zhangjiang Fudan International Innovation Center, Metabonomics and Systems Biology Laboratory at Shanghai International Centre for Molecular Phenomics, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Simultaneous analysis of multiple phosphorylated metabolites (phosphorylated metabolome) in biological samples is vital to reveal their physiological and pathophysiological functions, which is extremely challenging due to their low abundance in some biological matrices, high hydrophilicity, and poor chromatographic behavior. Here, we developed a new method with ion-pair reversed-phase ultrahigh-performance liquid chromatography and mass spectrometry using BEH C18 columns modified with hybrid surface technology. This method demonstrated good performances for various phosphorylated metabolites, including phosphorylated sugars and amino acids, nucleotides, NAD-based cofactors, and acyl-CoAs in a single run using standard LC systems.
View Article and Find Full Text PDFThe Elusive Ternary Intermediates of Chiral Phosphoric Acids in Ion Pair Catalysis─Structures, Conformations, and Aggregation.
J Am Chem Soc
January 2025
Institute of Organic Chemistry, University Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany.
In ion-pair catalysis, the last intermediate structures prior to the stereoselective transition states are of special importance for predictive models due to the high isomerization barrier between - and -substrate double bonds connecting ground and transition state energies. However, in prior experimental investigations of chiral phosphoric acids (CPA) solely the early intermediates could be investigated while the key intermediate remained elusive. In this study, the first experimental structural and conformational insights into ternary complexes with CPAs are presented using a special combination of low temperature and relaxation optimized N HSQC-NOESY NMR spectroscopy to enhance sensitivity.
View Article and Find Full Text PDFA dual experimental-theoretical perspective on ESPT photoacids and their challenges ahead.
Chem Sci
January 2025
Institut für Physikalische und Theoretische Chemie, Universität Regensburg 93040 Regensburg Germany +49 941 943 4487.
Photoacids undergo an increase in acidity upon electronic excitation, enabling excited-state proton transfer (ESPT) reactions. A multitude of compounds that allow ESPT has been identified and integrated in numerous applications, as is outlined by reviewing the rich history of photoacid research reaching back more than 90 years. In particular, achievements together with ambitions and challenges are highlighted from a combined experimental and theoretical perspective.
View Article and Find Full Text PDFHalide-free ion pair organocatalyst from biobased α-hydroxy acid for cycloaddition of CO to epoxide.
Org Biomol Chem
January 2025
State Key Laboratory Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhu Road South, Nanjing 211816, China.
The cycloaddition of CO to epoxide (CCE) reactions produce valuable cyclic carbonates useful in the electrolytes of lithium-ion batteries, as organic solvents, and in polymeric materials. However, halide-containing catalysts are predominantly used in these reactions, despite halides being notoriously corrosive to steel processing equipment and residual halides also having harmful effects. To eliminate the reliance on halides as cocatalyst in most CCE reactions, halide-free catalysts are highly desirable.
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